Satsuma hybrid named ‘Sonet’

ABSTRACT

A new Satsuma hybrid ( Citrus unshiu  X) designated the variety name of ‘Sonet’ is described. The novel characteristics of the fruit include early maturity, tighter rind and firmer fruit does not puff easily and has an improved flavour compared to known varieties of Satsuma ripening at this time.

Botanical/commercial classification: (Citrus unshiu X), new hybridSatsuma variety.

Variety denomination: ‘Sonet’. BACKGROUND OF THE INVENTION

‘Sonet’ is an open pollinated hybrid of an unpatented Citrus unshiuvariety ‘Miho Wase’ (unpatented) (the female seed parent). In 1996 openpollinated fruit was collected from ‘Miho Wase’ trees adjacent to Citrusreticulata varieties ‘Nova tangelo’ (unpatented), ‘Ellendale’(unpatented) and ‘Novelty’ (unpatented) (possible male pollen parents).The seeds from each fruit were extracted and planted. Zygotic seedlingswere selected in the nursery in 1997, by leaf morphology. The 14selected seedlings were budded to ‘Troyer citrange’ (unpatented)rootstocks and planted on a trellising and arching system in a forcinghouse, in 1998, situated in Addo, in the Eastern Cape province of theRepublic of South Africa (global positioning satellite co-ordinates 25°42′E.; 33° 34′S.). Due to the early maturing and fruiting of citrustrees grown on the trellising and arching system, the first fruit wasset in 2000. These trees were then evaluated for fruit quality traits.Based on the results of this evaluation, one of the aforementioned treeswas selected for further evaluation, resulting in the present ‘Sonet’variety. ‘Sonet’ was made subject of a South African Plant Breeders'Rights application on 5 Dec. 2006. This application was subsequentlygranted in 2009 under number ZA 20094289.

The time of fruit maturity (early to mid April), makes this selection anearly maturing variety. Good flavour (mandarin-like) and firm fruit witha good shelf life of at least four weeks from maturity make ‘Sonet’superior to the ‘Satsuma’ (unpatented) and early ‘Clementine’(unpatented) in the market at this time.

Trees bear a good to excellent crop from the fourth year after planting.Alternate-bearing has not been noted. There is a small percentage ofsplitting in February and as with all early maturing mandarin cultivars,some fruit are lost to sunburn.

‘Sonet’ was first asexually propagated in Addo, South Africa in 2000when buds were collected from a hybrid seedling designated WH/B/02/36(1740). Three trees were topworked onto ‘Carrizo citrange’ (unpatented)rootstocks and one tree onto a ‘Rosehaugh’ (unpatented) mandarinrootstock. These four trees of ‘Sonet’ were initially used forevaluation and description purposes. Two more trees were top worked onto‘F80/9 citrumelo’ (unpatented) rootstocks in 2001 for evaluationpurposes. In 2005 three budded nursery trees were planted out on ‘Troyercitrange’ rootstocks for evaluation. The first trialorchard of ‘Sonet’was planted at Addo in February 2006. This consisted of budded nurserytrees, 125 trees on ‘Carrizo citrange’ rootstock and 19 trees on ‘Troyercitrange’ rootstock. In 2009 a further 24 budded nursery trees on C35rootstock and four trees on ‘Carrizo citrange’ rootstock were plantedfor evaluation. All characteristics of the original tree and its fruitas determined and described appear to be transmitted through succeedingasexual propagations. No incompatibility or other rootstock relatedproblems have yet been observed. The mother tree is still growing in theforcing house on the trellising and arching system in a 20 liter pot, asof 2012, 14 years old. The tree is in a fair condition and is stillbearing good quality fruit.

Further, ‘Sonet’ has been cleansed of all graft transmissible virusesand viroids by shoot-tip grafting (STG), followed by pre-immunizationwith a light strain of the Citrus tristeza virus (LMS6). This was donethrough a regulated process, which involves taking vegetative buds fromthe mother tree and introducing the same into the South African CitrusImprovement Scheme. In this process, plant material is shoot-tip graftedto provide a virus-free source of bud wood material. Material soobtained is then pre-immunized with a mild strain of the aforementionedCitrus tristeza virus, followed by a certification by the relevant SouthAfrican citrus authority. In addition, ‘Sonet’ is free from Apple Stemgrooving virus (Capillovirus spp.), psorosis virus (Ophiovirus),Impietratura (Citrus impietratura agent (CSI000)), Citrus Viroids (CVDI: Genus Apscaviroid species: Citrus viroid CVd-I (CBLVd), CVD II: GenusHostuviroid species: Citrus viroid CVd-II (HSVd), CVD III: GenusApscaviroid species: Citrus viroid III (CVd-III), CVD IV: GenusCocadviroid species: Citrus viroid IV (CVd-IV), CVD V: Genus Apscaviroidspecies: Citrus viroid V (CVd-V)), and Exocortis (Family Pospiviroidae,Genus Pospiviroid, species citrus exocortis viroid CEVd).

The present variety is distinguishable over ‘Miho Wase’ Satsuma (Citrusunshiu) which is as the closest variety to ‘Sonet’, in the followingways. ‘Sonet’ differs in leaf morphology from the ‘Miho Wase’, maturesabout two weeks later than the ‘Miho Wase’, has a smoother firmer andtighter rind, does not puff easily, and has improved flavour over ‘MihoWase’. Fruit of ‘Sonet’ could contain some seed under cross pollinationconditions, while fruit of ‘Miho Wase’ will be seedless under similarconditions. ‘Sonet’ matures earlier than any of its possible male pollenparents.

BRIEF SUMMARY OF THE INVENTION

This invention relates to a new and distinct variety of a Satsuma hybrid(Citrus unshiu X), presently named ‘Sonet’ the novel characteristics ofwhich, under the local South African evaluation conditions, resideparticularly in the early onset of maturity of the fruit, as well as afirmer fruit rind, does not puff easily and has improved flavour over‘Satsuma’ and early ‘Clementine’ maturing at this time. Under localconditions, fruit maturity takes between 812 to 820 days afterfruit-set. Ploidy level is unknown but presumed to be polyploid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: is a photograph showing an entire ‘Sonet’ tree on ‘Carrizocitrange’ rootstock at four years of age;

FIG. 2: is a photograph showing crop load potential of ‘Sonet’ at threeyears of age;

FIG. 3: is a photograph of ‘Sonet’ fruit in perspective view showing itsgeneral shape;

FIG. 4: is a further photograph showing details of a typical ‘Sonet’fruit: viewed from top and bottom aspects showing the apex and base,respectively, together with a cross section through the fruit;

FIG. 5: is a photograph depicting a typical stem of ‘Sonet’, and inparticular showing bud union;

FIG. 6: is a photograph depicting a close up of the bark on ‘Sonet’;

FIG. 7: is a close-up photograph showing several leaves of ‘Sonet’,illustrating the sizes and shapes of the leaves, including the venationthereof;

FIG. 8: is a photograph showing florescence; and

FIG. 9: is a schematic illustration of the pedigree of ‘Sonet’.

DETAILED BOTANICAL DESCRIPTION

The detailed description below is based on four year old trees, unlessotherwise specifically stated to the contrary.

-   Tree: ‘Sonet’ trees are compact and Satsuma-like with a    Clementine-like leaf shape. The tree is precocious and heavy    bearing, and has a spreading growth habit. Thorns have been observed    on some nursery trees and on juvenile trees. However older bearing    trees have very small to no thorns. Observed juvenile thorniness is    probably attributable to shoot-tip grafting (STG). Thorniness    appears to be reduced and in some cases eliminated through    successive growth cycles, notably after the third successive flush.    The rootstock compatibility with ‘Carrizo citrange’ is good as    observed and indicated by stem measurements.    -   -   Size.—The average height of trees is 1.8 meters, measured            from soil level, with an average skirt height of 0.75            meters. The average spread (width) of trees is 1.5 meters.        -   Shape.—Obloid in shape.        -   Trunk.—The trunk has a fairly smooth surface texture and is            brown-green (RHS 200A and RHS 137A) in color. The average            trunk diameter is 24.0 centimeters measured at the bud            union. Average diameters of 19.5 centimeters and 25.5            centimeters were measured at heights of 15 centimeters above            and below the bud union, respectively. The average height of            the bud union is 28 centimeters, measured above soil level.        -   Branch.—Branches have a diameter of between 8.2 and 13.4            centimeters. There are between 5 and 8 main branches per            tree. Average crotch angles vary between 30° and 90°. The            smaller of the range of crotch angles is found among the            middle vertically growing branches forming the top of the            tree, and the larger of the range of crotch angles is found            between the vertically growing branches and the horizontally            growing branches, forming the sides of the tree. As with the            trunk, the branches have a fairly smooth surface texture and            are brown-green (RHS 199B and RHS 137A) in color.-   Flower:    -   -   Size and color.—The flower of ‘Sonet’ is typically            hermaphroditic. Its petals are yellow-white (RHS 158D) on            the inside and yellow-white (RHS 158D) with small yellow            (RHS 4B) speckles on the outside. Further, it has light            yellow (RHS 11A) anthers. Flowering occurs from September to            October in South Africa. Being a normal diploid Satsuma,            there is a small to medium amount of pollen with            approximately 63% viability depending on climatic            conditions, and as determined using the carmine-red stain            method. Flower buds are ovoid in shape and have an average            length of 11.5 millimeters and an average width of 6.1            millimeters. In addition, each flower has five petals.            Petals are elliptic in shape and have an average length and            width of 14.0 millimeters and 5.6 millimeters, respectively.            The petal tip is acute in shape, while the base is truncate.            The petal margin is entire. On a completely opened flower,            the typical calyx diameter averages 5.0 millimeters. There            are generally three to five flowers per cluster and the            flowers have a typical citrus flower fragrance.        -   Reproductive organs.—The style has a length of 5.5            millimeters, while the stigma and the style, in combination,            are approximately 7.2 millimeters long. The stamen has a            length of 7.4 millimeters. The style is white-green (RHS            145B), while the stigma is light yellow (RHS 11B) in an            unpollinated state. On average, there is one style and            stigma, and 14 to 20 stamens with anthers. The style with            the stigma is the same length as the stamens positioning the            anthers around, at the same height as, the stigma.-   Leaves: For purposes of the following leaf description, all leaves    were taken as the first leaf after the new flush growth.    -   -   Shape and size.—Leaves are simple, brevipetiolate and            lanceolate in shape, with very slight dentate incisions            along the blade margin. Blade emargination is not present at            the tip. The leaves also have typically pinnate venation.            The shape of the leaf apex is acute while the base is            cuneate. In cross-section, the blade shape is straight but            fairly concave. The length of a typical leaf blade is            approximately 80.2 millimeters in length and the leaf blade            also has a width of approximately 28.5 millimeters. The            ratio of length:width of the typical leaf is 2.8:1.            Generally speaking, the shape and size of the 4-year old            ‘Sonet’ trees differ from the mother tree in that the leaves            are smaller and narrower in shape and are lighter in colour.            Leaf twisting and blistering are both absent or weak.        -   Petiole.—Wings are present but not prominent and are linear            and narrow. Width of the wings is 2 millimeters. Length of            the petiole is approximately 11 millimeters.        -   Color and surface texture.—The adaxial (leaf upper) surface            is darker (RHS 137A), in comparison to the abaxial (leaf            lower) surface (RHS 137C). The leaf upper and lower surfaces            are smooth and leaf veins are not prominent.-   Fruit, external characteristics:    -   -   Color.—The rind color is Yellow-green (RHS 15A and 17A) to            Yellow-orange (RHS 21A and 23 A) when the fruit is fully            mature.        -   Rind.—Fruit is easy to peel and the rind has an average            thickness of 1.5 to 2 millimeters. The strength of the fruit            rind is weak to medium.        -   Oil glands.—Small oil glands are present, not protruding and            are uniform in size. Oiliness is dry to medium.        -   Surface.—Pubescence is absent on the fruit surface, and the            fruit surface is fairly smooth in appearance. Overall, the            fruit has a medium glossy appearance (UPOV 5 — see ON 285            TG/201/1).        -   Shape.—With reference to the Citrus descriptors of the            previously named International Plant Genetic Resources            Institute (IPGRI), now known as Biodiversity International,            the shape of ‘Sonet’ is obloid, having its broadest part in            the middle of the fruit. The general shape of the proximal            part (stem end) of the fruit is slightly rounded with a            slight ruffling around the stem, while the fruit apex            (flower end) is depressed.        -   Size.—Fruit is on average 42 millimeters in length and 65 to            85 millimeters in diameter. Individual fruit mass varies            between 68 grams to 96 grams with an average mass of 83            grams per fruit (see Table 1 below) on ‘Carrizo citrange’            rootstock. The fruit length:diameter ratio is 0.742.        -   Base.—Depressed.        -   Calyx.—Slightly rounded.        -   Apex.—Slightly rounded.        -   Areola.—Present and smooth, with a diameter of 21.1            millimeters.        -   Stylar scar.—Present, but small in size.-   Fruit, internal characteristics:    -   -   Color.—The internal flesh color is orange (RHS 23A) to dark            orange (RHS 24A) when the fruit is fully mature.        -   Navel.—Absent when fruit is viewed internally.        -   Glandular layer.—Thickness of the rag is normal and slightly            tough.        -   Mesocarp (albedo).—The adherence of the albedo to the pulp            is weak and thus the peel is reasonably easy to remove from            the pulp. No albedo strands are left behind after such            removal. The albedo color is yellow-orange (RHS 158D). The            albedo has medium density. The albedo has medium density.        -   Axis.—Fruit has an open core with a diameter of            approximately 15 millimeters. Further, the core has sparse            to no filling.        -   Segments.—Each fruit has ten to twelve segments, and on            average there are eleven well-developed segments per fruit.            Strength of the segment is medium.        -   Pulp.—The pulp is fine with large cells. In a transverse            section of the fruit, the shape of the fruit pulp is            scalloped.        -   Neck/collar.—A collar on the fruit is sometimes present, but            mostly absent. Height of the collar when present is low to            medium. Diameter of the collar when present is 26.4            millimeters. Neck on the fruit is absent.        -   Juice.—Fruit is juicy with a good flavor that is aligned            towards a mandarin-like flavour. Juice is yellow-orange (RHS            21B) in color. Fruit have an average juice percentage of            59.5% on ‘Carrizo citrange’ rootstock. As indicated by the            solids:acid ratio (see Table 1), the best time to harvest            fruit under South African conditions is early to mid April.        -   Seeds.—Seeds are mostly clavate in shape (about 75%),            however some are semi-deltoid in shape (about 25%), with a            mostly wrinkled surface. In this regard, approximately 30%            of the seed surface tends to be smooth. The clavate shaped            seeds have an average length of 10.3 millimeters and an            average width of 4.8 millimeters, while the semi-deltoid            shaped seeds have an average length of 8.0 millimeters and            an average width of 6.0 millimeters. Further, the seeds have            a grey-white (RHS 196B) external color, and are green (RHS            160B) and highly poly-embryonic after removal of the testa.            This variety is parthenocarpic. However it contains few (1            to 3) to no seeds in solid blocks (as seen in Table 1). In            mixed blocks where cross pollination is present, fruit do            contain more seed.

TABLE 1 ‘Sonet’ Satsuma hybrid: Internal Quality Tests - 2010 (trees 4years old, planted in 1996) Addo, Eastern Cape, South Africa: Percentagefruit with Avg. Fruit Root- Juice Brix Acid Brix:Acid 0 1-3 4-6 7+ MassCultivar stock Test date % % % Ratio seed per fruit (grams) ‘Sonet’Carrizo 24 Mar. 2010 60.0 12.0 1.34  9.0 62 18 5 3 79.1 ‘Sonet’ Carrizo20 Apr. 2010 59.0 12.6 1.00 12.6 54  8 0 1 85.5

TABLE 2 Internal Quality Tests (trees topworked in 2000 to ‘Carrizocitrange’ rootstocks) Addo, Eastern Cape, South Africa: Test Date Juice% Brix % T. Acid % Brix/TA Ratio 14 Apr. 2008 67.4 11.8 1.08 10.9 09Apr. 2010 58.2 9.8 1.05 9.3

-   -   -   Yield.—The average fruit yields across the time period            2009-2010 appear in Table 3 below:

TABLE 3 Average Fruit Yield (2009-2010) Addo, Eastern Cape, SouthAfrica: Year 2009 2010 Tree age (years) 3 4 Yield (kg fruit/tree) 20.132.9 Yield (ton/ha) 11.1 18.3

The fruit of ‘Sonet’ is intended for human consumption. Fruit stored andshipped at 4° C., and kept under these conditions, are likely to keepfor up to six weeks. Data of a cold sterilization trial indicate that91% of the fruit is marketable after storage for 32 days at −0.5 Celsiusand 7 days at ambient temperature. Optimal protocols for degreening andwaxing is required for extension of shelf life. The time of maturity ofthe fruit is end-March to mid-April, which makes this selection an earlymaturing variety. The variety is self-compatible.

The above-described new variety of Satsuma hybrid displays a distinctearly expression of maturity (early to mid April), as well as animproved flavour and firmer fruit and tighter rind and does not puffeasily, compared to known varieties of Satsuma ripening at this time.

What we claim is:
 1. A novel and distinct Satsuma hybrid tree having thecharacteristics described and illustrated herein.